What one person said about some other issue years ago is irrelevant to the question at hand.
Just for fun, here's another irrelevant quote:
“There’s nothing in the Constitution that says the president stops being president in his last year.”
- Ruth Bader, on whether the Senate should hold hearings and a vote on the Supreme Court nomination of Merrick Garland
In short, it’s not the President’s fault. He should nominate someone. Mitch is the one who said the Senate should not vote. The Majority Leader does have some say over the duties of the Senate as it’s up to him to bring the vote. If it doesn’t change the duties and he was derelict of his 4 years ago then I would have hoped to see some repercussions.